1. Field of the Invention
The present invention relates generally to lighting applications, and more particularly to a display device comprising an organic light emitting material.
2. Description of the Related Art
There has been a longstanding desire to make inexpensive signs that can be read in the dark. A conventional approach is to utilize a glass or plastic plate with one or more color filters positioned such that the desired sign is created when placed over a backlight. An example of this is the common xe2x80x9cEXITxe2x80x9d sign. This technology, however, is not easily customizable, because the end user is not able to easily design and create such a sign. Most end users do not have the necessary tools or expertise to make the filter plate themselves. Instead, the end user must obtain the services of a filter plate manufacturer to create a customized sign. Most end users do not follow through with such an endeavor.
Many technologies have been developed to allow more customizable signs that can be read in the dark. Most of these are variations on a cathode ray tube (CRT) display. Such displays can be quickly reconfigured electronically to display a new sign. Other technologies with the same capability include liquid crystal displays, thin-film plasma displays, and organic electroluminescent displays. However, these displays require complicated electronics and are too expensive for many simple display sign applications.
Consequently, there is a longstanding need for a simple, inexpensive illuminated sign which can be easily customized by an end user.
The invention relates to a luminescent display comprising a first electrode, a second electrode, an organic light emitting layer disposed between the first and second electrodes, and a luminescent material which receives light from the organic light emitting layer and converts the light to a different wavelength, wherein the first and second electrodes together define an overlap region in which the organic light emitting layer is activated to emit light, and the luminescent material is disposed in a portion of the overlap region.
The invention also relates to a phosphor in solution, a light emitting device comprising a first electrode, a second electrode, and an organic light emitting layer, and means for applying the phosphor onto the light emitting device. The means for applying may comprise a printer cartridge containing at least one phosphor, for example. The printer cartridge may be used to print the luminescent material onto the light emitting device. The means for applying may also comprise a manual implement such as paint brush, a stamp, or a pen. The phosphor solution can be painted, stamped, or written on the light emitting device in any desired pattern and color.
The invention also relates to a method comprising the steps of creating an image and printing the image on a light emitting device comprising an organic light emitting layer after the light emitting device has been formed. The image may be created, for example on a personal computer, and printed with an inkjet printer. The image may be printed in phosphors which emit light of one wavelength upon absorbing light of a different wavelength from the organic light emitting layer.
Various embodiments of the invention allow customized luminescent displays to be easily fabricated by end users by applying a phosphor pattern to a preformed, encapsulated light emitting device. The light emitting device typically comprises an organic light emitting layer which provides illumination over a large surface area. The phosphor pattern can be applied to the light emitting device in a number of ways available to end users, such as with a computer printer or a manual implement. The availability of computer generated images allows end users to create professional quality luminescent displays with minimal investment in equipment.